Hmm ... It's impossible ;-) This RPM doesn't exist on any FTP server

Provides :
gcc81
gcc81(x86-64)
libcc1plugin.so.0()(64bit)
libcp1plugin.so.0()(64bit)
liblto_plugin.so.0()(64bit)

Requires :

libc.so.6()(64bit)
libmpc.so.3()(64bit)
libstdc++.so.6(GLIBCXX_3.4)(64bit)
libm.so.6(GLIBC_2.2.5)(64bit)
libc.so.6(GLIBC_2.3.3)(64bit)
libstdc++.so.6(CXXABI_1.3)(64bit)
libgcc_s.so.1(GCC_3.0)(64bit)
libstdc++.so.6(CXXABI_1.3.9)(64bit)
rpmlib(PayloadIsXz) <= 5.2-1
libquadmath0 = 8.1.0-5.26.el7
libgo.so.13()(64bit)
ld-linux-x86-64.so.2(GLIBC_2.3)(64bit)
libasan5 = 8.1.0-5.26.el7
libdl.so.2()(64bit)
libgmp.so.10()(64bit)
libc.so.6(GLIBC_2.14)(64bit)
libc.so.6(GLIBC_2.2.5)(64bit)
libc.so.6(GLIBC_2.3.4)(64bit)
libmpx2 = 8.1.0-5.26.el7
libisl.so.15()(64bit)
libgomp1 = 8.1.0-5.26.el7
/bin/sh
libstdc++.so.6()(64bit)
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
libpthread.so.0(GLIBC_2.2.5)(64bit)
libpthread.so.0()(64bit)
libmpfr.so.4()(64bit)
cpp81
ld-linux-x86-64.so.2()(64bit)
rpmlib(CompressedFileNames) <= 3.0.4-1
rpmlib(FileDigests) <= 4.6.0-1
rpmlib(PartialHardlinkSets) <= 4.0.4-1
libc.so.6(GLIBC_2.15)(64bit)
libatomic1 = 8.1.0-5.26.el7
libm.so.6()(64bit)
libc.so.6(GLIBC_2.3)(64bit)
libc.so.6(GLIBC_2.11)(64bit)
libgcc_s.so.1()(64bit)
libstdc++.so.6(CXXABI_1.3.8)(64bit)
libdl.so.2(GLIBC_2.2.5)(64bit)
binutils
/sbin/ldconfig
libz.so.1()(64bit)
glibc-devel
libubsan1 = 8.1.0-5.26.el7

Content of RPM :
/usr/bin/gcc-8.1
/usr/bin/gcc-ar-8.1
/usr/bin/gcc-nm-8.1
/usr/bin/gcc-ranlib-8.1
/usr/bin/gcov-8.1
/usr/bin/gcov-dump-8.1
/usr/bin/gcov-tool-8.1
/usr/lib/bfd-plugins
/usr/lib/bfd-plugins/liblto_plugin.so.0
/usr/lib64/gcc
/usr/lib64/gcc/x86_64-redhat-linux-gnu
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/buildid
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/cc1obj
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/collect2
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtbegin.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtbeginS.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtbeginT.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtend.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtendS.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtfastmath.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtprec32.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtprec64.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/crtprec80.o
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/include
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/include-fixed
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/include-fixed/README
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/include-fixed/limits.h
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/include-fixed/linux
/usr/lib64/gcc/x86_64-redhat-linux-gnu/8.1.0/include-fixed/linux/a.out.h
There is 620 files more in these RPM.